A green method for the acylation of secondary alcohols with [CholineCl][ZnCl2]3-catalyzed by ultrasonic method

Abstract

DES (deep eutectic solvents) [CholineCl][ZnCl2]3, which easily prepared from choline chloride and zinc chloride (ZnCl2), is useful for the acylation of secondary alcohols with acid anhydrides. Acylation of alcohols with acid anhydrides as acylating reagent using [CholineCl][ZnCl2]3 as a catalyst was investigated under the ultrasonic method. Six secondary alcohols were investigated and afforded high yields (88-96%). The desired products were characterized by NMR and GCMS spectra. Different from traditional Lewis acidic catalysts, [CholineCl][ZnCl2]3 was found to be an efficient catalyst for acylation of alcohols under mild conditions. By using the ultrasonic method, the processes gave high yield; the catalyst is cheap, easy to handle, recyclable for several times without significant loss of the catalytic activity.